Hi Virginia, I didn't find anything other than the 1800 Census with them listed either.
Before you ask for an obituary or death notice, you need to know when and where Annie Sophia died. Before 1905 in California, vital records were recorded in the counties. You can file a request for her death record at the Humboldt County Recorder's Office, http://co.humboldt.ca.us/recorder/docs/vital_records.asphttp://co.humboldt.ca.us/recorder/docs/vital_records.asp .
I don't know how much looking the County Recorder will do and you have need another volunteer. There are several at Random Acts Genealogical Kindness. Go to www.raogk.org, read guidelines, choose California, choose Humboldt County and choose one volunteer. Successful Searching!